1. Field of the Invention
This invention relates to a blind attachment equipped with a self-breaking holding system.
2. Description of the Related Art
A blind attachment makes it possible to assemble parts while having access only to a single side of the assembly.
As illustrated in FIG. 2, a blind attachment comprises a body 10 that comprises a bore 12 in which a rod 14 is housed with a head 16 at a first end and whose other end 18 projects relative to the body 10 in such a way as to be able to be gripped by a tool. A sleeve 20 that is also called a bulb is arranged between the head 16 and the body 10.
To ensure the translational motion of the rod 14, one approach consists in providing a threaded rod 14 that is screwed into a threaded bore 12 of the body 10. The end 18 of the rod 14 comprises at least one flat surface for making it possible for a tool 22 to drive the rod 14 in rotation.
As illustrated in FIG. 2, the surface 24 of the body oriented toward the tool 22 comprises slots 26 (hollow shape) that make it possible to immobilize the body 10 in rotation so that the rotation of the rod 14 creates a relative translational motion between the rod 14 and the body 10.
According to one embodiment, a nut 28 can be interposed between the tool 22 and the surface 24 of the body.
According to an operating method, in a first step, the blind attachment is put into a bore 30 made in the parts 32 to be assembled, as illustrated in FIG. 1A. When the tool 22 drives the rod 14 in rotation, this tends to deform the sleeve 20 gradually, as illustrated in FIGS. 1B and 1C, which, after creep, flattens itself against the surface that is inaccessible after the assembly. When the sleeve 20 is completely deformed, the force in the threaded rod 14 becomes too great so that the latter breaks as illustrated in FIG. 1D.
Subsequently, it is advisable to plane down the threaded rod so that the latter is flush with the surface 24 of the body.
After the installation of the blind attachment and the application of paint, the slots 26 remain visible. Consequently, this type of attachment is not entirely satisfactory in terms of esthetics.
According to another point, when these slots 26 are arranged at the surface of the fuselage, they form rough spots that create disturbances on the aerodynamic plane.